Disassembly: Manifold Pressure Differential Sensor

[Greg E]

It's late and I'm very tired so I'm not going to get into too much detail about this.

The stock MDP sensor is a simple 1bar sensor on top of the plenum in OBD2 cars to monitor if there's positive pressure in the plenum so the ECU knows when to shut the purge and EGR valves.

For a while now, I've been testing the EVO X map sensor in my car. The idea is to datalog boost pressure using EVOScan and the flashable ECU. The EVO 10 uses a 3.25 bar MAP sensor that can measure up to 32 psi of boost. This sensor is nearly identical in appearance to the stock sensor, so it can be easily swapped in for some plug and play fun.

If you pop off the stock sensor, you'll see a space with a small hole. I believe this cavern is just an area to keep air turbulence away from the sensor so the readings are more accurate.



Here are the 2 sensors side by side. Note: the EVO 10 sensor is the one with the yellow cap on it.





No one would have a clue...


Part number for this sensor is 1865A052 and it's available for $145.16 plus shipping thru MitsubishiParts.net - Your #1 Source for OEM Parts and Accessories

Anyone who is running or planning to run the EVOX MAP sensor, you will need this information in order to keep the periphery bit enabled and pass emissions. Go ahead and add this to your V1 Chromed ROM.

V2 update! Since I've figured out how the emissions tests work, most of these values do not need to be updated. Only the EGR Offset table. I've also eliminated the second EGR table (both tables were the same values anyway).



Change the EGR MAP Offset table to the following values:

750 84
1000 84
1250 73
1500 65
1750 60
2000 55
2500 48
3000 43
3500 23



In V2 you need to set the sensor scaling in order for EVOScan to show accurate numbers. Here are the settings!



These values are ONLY for the EVO 10 MAP sensor! I have no clue how to make any of the other sensors out there work with the emissions.

[TurboSinceBirth]

I was actually just looking at the pinout for the manifold pressure differential sensor wondering what in the world I would be using it for but now I know. I might keep this in mind although I think I was going to have EVOScan get boost from my BlackStealth LCD boost controller.

[Greg E]

I was actually just looking at the pinout for the manifold pressure differential sensor wondering what in the world I would be using it for but now I know. I might keep this in mind although I think I was going to have EVOScan get boost from my BlackStealth LCD boost controller.

I'm trying to find the MAP sensor voltage scaling table. Although this patch fixed the OBD2 check, idle is still lopey.... Just so you're aware!

If you're an OBD1 car, disabling the peripheries for the MAP and EGR work just fine. I did this dis-assembly so OBD2 guys can still use this sensor an pass inspection.

[Greg E]

Just confirmed that my car passed OBD2 inspections with these settings for EVOX map sensor!

Also figured out why the idle is lopey. The periphery0 EGR bit is backwards! Leaving it switched to 0 means it's enabled. Switching it to 0 screws with the write to R0 for the next sub. I will patch this in V2 so it works like we think it should.

[awdonly]

I'm trying to find the MAP sensor voltage scaling table. Although this patch fixed the OBD2 check, idle is still lopey.... Just so you're aware!

If you're an OBD1 car, disabling the peripheries for the MAP and EGR work just fine. I did this dis-assembly so OBD2 guys can still use this sensor an pass inspection.

Thanks Greg - I'm planning on installing an EVO X MAP in my '95 (got an adapter and pigtail) and will be hooking it up to pin 92 of the ECU (its also feeding my LCDBoostController). Will this setup allow me to enable peripheries for the MAP and EGR to get EGR to operate normally? Will it add any other value/functionality asside from ECU boost control?

[Greg E]

Yes it will.

Not right now.

[awdonly]

Thanks Greg,

Will these changes solve the evap purge solenoid clicking problem as well? If not, how do I disable?

[Greg E]

You're going to need the patch to bypass the fuel tank pressure sensor. This will come in V2. If you're interested, I need a beta tester.

For now, just unplug the solenoid. It shouldn't be clicking if you have bit 15 of periphery 2 disabled though.

[awdonly]

I can help beta test, but I don't have a stock set-up for a '95 (Cali) since I added the evo x map sensor.

Let me check that bit again when I get home.

[Greg E]

Doesn't matter if you're setup for Cali emissions or not. When OBD2 became standard every car had to pass the same laws statewide. All years/models had to have a purge system. The 98/99 ECU handled that system a bit differently. It my hopes this patch will still keep that function without the added sensor from the 98/99 car.

All I'd like you to test is if the solenoid works with my ROM or not. Seems to work on my car but it would be wise to confirm its functionality on a few vehicles before going public.